1. Field of the Invention
The present invention relates to pumps and particularly to rotating pumps employing axial shaft seals.
2. Description of the Related Art
Impeller type pumps such as regenerative turbine pumps are shaft driven and normally employ housing shaft seals. A typical seal includes a housing carried stationary seal member and a shaft carried rotating seal member with the seal members axially urged into face to face abutment. Since the seal is a wear item, it is necessary to provide access to the seal for disassemblability of the seal and replaceability of the seal or components thereof. This normally involves disassembly of a major portion of the pump to provide access to the seal components.
Difficulty in disassembly is compounded by the fact that the rotating portion of the seal must be fixed to the shaft for rotation therewith and axially positioned with respect to the stationary seal portion.
Since access to and ease of disassemblability and removability of the shaft seal, the principal wear component of the pump, is a critical factor in pump maintenance, improvement of ease of repair and replacement represents a significant advance in pump design.
This invention provides improved assembly, disassembly and repair of pumps and in particular regenerative turbine pumps by providing a pump assembly which includes a housing member defining a turbine chamber and a seal chamber with the turbine chamber closed by an end cap. The shaft extends from a bearing mount through the seal chamber and into an internal recess in the end cap. The shaft passes through a stationary seal face at the entrance to the seal chamber. A rotating seal assembly is positioned on the shaft intermediate the stationary seal member and the impeller and is commonly keyed to the shaft in a key groove in the shaft which receives a locking key positioning the impeller. A snap-ring received in a groove in the shaft provides axial positioning of the rotating seal assembly. By providing a common rotational mount for the impeller and the rotating shaft assembly utilizing a single key groove in the shaft, ease of access, disassembly and removability of the shaft seal is provided. Upon removal of the end cap, the impeller can be slid off the shaft through the open end thus giving direct access to the snap-ring. Because the key groove is common for both the mount of the impeller and the rotating shaft seal, upon removal of the impeller key the seal assembly can be slid off the shaft for replacement. Removal of the rotating shaft assembly provides direct access to the stationary seal ring.
In an embodiment of the invention, an impeller pump is provided with a drive shaft having a key groove therein and a rotating shaft seal assembly carried by the shaft is rotationally fixed to the shaft via the key groove which also rotationally fixes the impeller.
In an embodiment of the invention, a pump housing is provided having an impeller wheel pumping housing section which includes a seal opening for a shaft seal with a common shaft extending into the seal opening through a stationary portion of a shaft seal, the shaft having a key groove, the rotating assembly portion of the shaft seal being carried on the shaft and keyed to the shaft in the key groove, the impeller being carried on the shaft and keyed to the shaft in the same key groove as the rotating seal assembly.
In a further embodiment of the invention, a regenerative turbine pump is provided having a multi-part housing including a bearing housing section, an end-cap section, and a seal and pumping chamber positioned between the bearing section and the end-cap section. A common shaft extends through the bearing section, the seal section and into a portion of the end-cap and is provided with a key groove. An impeller wheel is mounted on the shaft and keyed to the shaft via the key groove. A seal assembly is mounted in the seal area including a rotatable section mounted to the shaft and keyed thereto by the same key groove. A stationary shaft seal portion is carried by the intermediate housing at the juncture with the bearing housing portion. All portions of the shaft seal are accessible upon removal of the end cap, the impeller and the impeller shaft key.
Other features and objects of the invention will be apparent to those skilled in the art from the following description of the preferred embodiment.